Equol-containing extract, method for production thereof, method for extraction of equol, and equol-containing food

Abstract

The present invention relates to an extract obtained by extracting useful components containing equol from an equol-containing fermented soybean hypocotyl, and to a method for producing the same. The present invention makes it possible to efficiently obtain useful components containing equol from the fermented soybean hypocotyl by subjecting an equol-containing fermented soybean hypocotyl to extraction using an ethanol aqueous solution as an extractant. The present invention reduces the content of saponin, which causes an unpleasant taste, by sequentially subjecting the equol-containing fermented soybean hypocotyl to extraction using an ethanol aqueous solution and ethanol, while efficiently extracting equol and glycitein.

The invention claimed is: 
     
       1. A method for producing an equol-containing extract comprising:
 Step I-1 of subjecting an equol-containing fermented soybean to extraction using an aqueous ethanol solution containing between 65-90% ethanol as an extractant, to thereby produce a first liquid extract and a first residue, and collecting said first liquid extract; and 
 Step I-2 of removing the aqueous ethanol extractant from said first liquid extract to thereby produce a second residue, conducting extraction on said second residue using absolute ethanol as an extractant, and collecting the liquid resulting from said extraction on said second residue, wherein the saponin content in the equol-containing extract is reduced. 
 
     
     
       2. The method for producing an equol-containing extract according to  claim 1 , wherein the equol-containing fermented soybean is obtained by fermenting a soybean with an equol-producing microorganism. 
     
     
       3. The method according to  claim 1 , which further comprises:
 Step I-3 of removing a solvent from said liquid collected in Step I-2, suspending the resulting residue in hexane, and then collecting the insoluble residue; 
 Step I-4 of subjecting the insoluble residue obtained in Step I-3 to extraction using a mixture of hexane and ether as an extractant, and then collecting the resulting liquid extract; and 
 Step I-5 of subjecting the liquid extract obtained in Step I-4 to silica gel column chromatography, and obtaining an equol-containing fraction. 
 
     
     
       4. The method according to  claim 1 , wherein the equol-containing extract is in a form suitable for food. 
     
     
       5. The method according to  claim 1 , wherein the equol-containing extract contains glycitein compounds. 
     
     
       6. A method for producing an equol-containing extract comprising:
 Step I-1 of subjecting an equol-containing fermented soybean to extraction using an aqueous ethanol solution as an extractant, to thereby produce a first liquid extract and a first residue, and collecting said first liquid extract; 
 Step I-2 of removing the aqueous ethanol extractant from said first liquid extract to thereby produce a second residue, conducting extraction on said second residue using ethanol as an extractant, and collecting the liquid resulting from said extraction on said second residue; 
 Step I-3 of removing a solvent from said liquid collected in Step I-2, suspending the resulting residue in hexane, and then collecting the insoluble residue; 
 Step I-4 of subjecting the insoluble residue obtained in Step I-3 to extraction using a mixture of hexane and ether as an extractant, and then collecting the resulting liquid extract; and 
 Step I-5 of subjecting the liquid extract obtained in Step I-4 to silica gel column chromatography, and obtaining an equol-containing fraction. 
 
     
     
       7. The method for producing an equol-containing extract according to  claim 6 , wherein the ethanol concentration of the aqueous ethanol solution used in Step I-1 is 20 to 98 vol. %. 
     
     
       8. The method for producing an equol-containing extract according to  claim 6 , wherein the equol-containing fermented soybean is obtained by fermenting a soybean with an equol-producing microorganism. 
     
     
       9. The method according to  claim 6 , wherein the equol-containing extract is in a form suitable for food. 
     
     
       10. The method according to  claim 6 , wherein the equol-containing extract contains glycitein compounds.